Journal of Equine Veterinary Science 31 (2011) 722-731

Journal of Equine Veterinary Science

journal homepage: www.j-evs.com

Original Research Midline Cysts of Colliculus Seminalis Causing Ejaculatory Problems in Stallions

Malgorzata A. Pozor DVM, PhD, Dipl ACT a, Margo L. Macpherson DVM, MS, Dipl ACT a, Mats H. Troedsson DVM, PhD, Dipl ACT, ECAR c, Claudia Klein DVM, PhD, Dipl ACT, ECAR c, Mohamadou Diaw DVM a, Claus Buergelt DVM, PhD, Dipl ACVP b, Liane Dillon a a Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL b Department of Infectious Diseases and Pathobiology, University of Florida, Gainesville, FL c Department of Veterinary Science, University of Kentucky, Lexington, KY article info abstract

Article history: Cystic structures are often seen during ultrasound examination of the internal genitalia Received 4 March 2011 of stallions. They are located between the ampullae of deferent ducts, either within the Received in revised form urogenital fold, or under the isthmus of the (uterus masculinus). Occasionally, 03 May 2011 cystic dilatations are also found more caudally, behind the prostate, at the colliculus Accepted 8 June 2011 seminalis (urethral cyst, utriculus masculinus). These cysts are detected less frequently Available online 27 July 2011 during routine examinations, possibly because of the fact that this area is screened less carefully for the pathologies than the more proximal portion of the internal reproductive Keywords: Midline cyst tract of stallions. We have recently noticed that many stallions with ejaculatory problems Utriculus have large cysts at the colliculus seminalis. This article describes the typical clinical Uterus masculinus presentation of these cases, diagnostic procedures, and management. In addition, we Ejaculatory dysfunction discuss the discrepancies in the currently used terminology pertinent to this condition, Stallion as well as introducing a new term, which seems to best describe the root cause of this disorder. Finally, this article presents new diagnostic and therapeutic options used in human medicine in similar cases, and proposes to investigate the applications of these methods in veterinary medicine. Ó 2011 Elsevier Inc. All rights reserved.

1. Introduction dysfunctions that are associated with partial or complete occlusion of the ampullae [3] . Ejaculatory dysfunctions in stallions occur rarely but Uterus masculinus, which is a cystic remnant of the are frustrating for horse breeders [1] . Various musculo- Müllerian ducts, has been occasionally associated with skeletal and neurologic diseases are responsible for ejaculatory problems in stallions [4]. However, this struc- the majority of these disorders, whereas only a small ture is also identi fied in stallions with normal ejaculatory percentage of them is associated with the ejaculatory patterns [5,6]. It is most often located between the terminal apparatus itself [1,2] . Diagnosis of speci fic causes of parts of the ampullae of deferent ducts, within the urogen- these dysfunctions is dif ficult and often unrewarding. ital fold, on the dorsal side of the bladder; or on the level of Dilatation of the terminal portion of the ampullae of the neck of the urinary bladder, underneath the prostatic deferent ducts, visualized during transrectal ultrasound isthmus (Fig.1A). A small lumen is often present in the mid- evaluation (TRUS), is often reported in cases of ejaculatory portion of this structure, which can be identi fied in many stallions during a routine ultrasound evaluation. Secretions Corresponding author at: Malgorzata A. Pozor, DVM, PhD, Dipl ACT, of the glandular epithelium may become trapped within this University of Florida, College of Veterinary Medicine, PO Box 100136, Gainesville, FL. lumen and may form cysts of various sizes and shapes E-mail address: pozorm@ufl.edu (M.A. Pozor). (Fig. 1B). Anterior part of the uterus masculinus often gives

0737-0806/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2011.06.004 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 723

Fig. 1. Internal genitalia in stallion (ub ¼ urinary bladder, a ¼ ampulla of deferent duct, v ¼ vesicular gland, p ¼ lobe of prostate, bu ¼ , u ¼ , m ¼ uterus masculinus, c ¼ colliculus seminalis, um ¼ opening to utriculus masculinus, * ¼ cyst). (A) Dorsal view. ( B) Various locations of cysts. (C) Ventral view with the urethra cut open. off two cornua with blind ends. The posterior end, called a separate clinical entity, which deserves recognition by utriculus masculinus, continues its course beyond the practicing veterinarians. prostate, and opens into the urethra on the summit of the colliculus seminalis (Fig. 1C). Lack of this opening may lead 2. Presentation to the formation of a cyst at the colliculus seminalis, called , cystic enlargement of utriculus masculinus, Typically, stallions with ejaculatory problems, associ- or urethral cyst ( Fig. 2A) [4,7]. Large cysts at this location ated with the midline cysts of the colliculus seminalis, may interfere with emission and the ejaculatory process in present to the clinic with a complaint of inconsistent some stallions (Fig. 2B) [6] Significant compression of the reproductive performance. They have periods with normal ejaculatory ducts (EDs) leads to a build-up of fluids in the sexual behavior and good quality, alternating with ampullae of deferent ducts and in the excretory ducts of the days or weeks of ejaculatory problems and/or poor semen vesicular glands. Small cellular concrements or large solid quality. Treatment with oxytocin and transrectal massage plugs form in the very terminal parts of deferent ducts as of the accessory glands only occasionally helps in a consequence of a long-term spermiostasis ( Fig. 2C). Gel obtaining an ejaculate, but these procedures are not secreted by the vesicular glands becomes very thick, dif ficult effective on many occasions. Frequent semen collections do to expel, and may completely plug the EDs. not prevent an occurrence of this disorder. There are also We have recently examined 10 stallions with cysts at cases, which present with a consistent history of long-term the colliculus seminalis, which contributed to the long- ejaculatory problems or infertility. term problems with the ejaculatory process ( Table 1 ). These cysts were located between the caudal edge of the 3. Evaluation prostate and the cranial pole of the bulbourethral glands, at the level of the colliculus seminalis. The affected stallions Evaluation of stallions with ejaculatory disorders showed a similar pattern of copulatory behavior, and follows the outline of the breeding soundness evaluation similar physical features in their internal reproductive recommended by the Society of Theriogenologists [8]. tract. Therefore, in this article, we describe this disorder as However, some modi fications are usually made.

Fig. 2. Pelvic urethra (cross-section) at the level of colliculus seminalis in a stallion (u ¼ urethra, c ¼ colliculus seminalis, v ¼ excretory duct of the vesicular gland, d ¼ terminal part of deferent duct, e ¼ , * ¼ utriculus masculinus). (A) Diagram with normal utriculus masculinus communicating with a urethra. (B) Diagram with enlarged utriculus masculinus not communicating with a urethra (cyst of colliculus seminalis). ( C) Diagram with a cyst of colliculus seminalis, dilated excretory ducts of vesicular glands with thick plugs, and terminal parts of deferent ducts with solid concrements. 724 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731

Table 1 Clinical examples of stallions with the midline cysts of the colliculus seminalis

Case Age Breed Presenting Sexual Behavior Semen Shape Largest Dimension Number Year Complaint Characteristics of a Cyst of a Cyst (cm)

1 13 TB BSE Ejaculatory difficulties Normal Oval 1.13 2 17 QH Ejaculatory Ejaculatory difficulties Asthenozoospermia; Oval Spindle 1.0 difficulties bacterial plugs shape 4.0 3 10 QH Occasional Occasional ejaculatory Occasional Tear shape 1.5 Asthenozoospermia difficulties Asthenozoospermia 4 5 Paso Fino Short longevity of Strong stimulation Short longevity of Oval 1.5 sperm motility necessary sperm motility 5 13 Tennessee Azoospermia, Ejaculatory difficulties; Azoospermia, large Oval 1.5 Walking tailless heads discomfort percentage of tailless Horse heads of spermatozoa 6 8 Miniature Ejaculatory Ejaculatory difficulties High concentration Oval 0.54 Horse difficulties of spermatozoa; bacterial plugs 7 7 TB BSE Ejaculatory difficulties Normal Oval 1.13 8 4 Paint Anejaculation Ejaculatory difficulties Normal Oval and 1.2; 0.9; 0.5 rectangular (multiple) 9 8 Irish Draft Infertility Anejaculation Azoospermia Tear shape 1.2 10 4 Paso Fino Asthenozoospermia Low ; strong Oligospermia; Oval 1.5 stimulation necessary Necrospermia

3.1. Sexual Behavior associated with the midline cyst of the colliculus seminalis retain strong sexual drive despite their symptoms. Stallions After conducting a complete physical examination of with occluded ampullae thrust multiple times, and often the affected stallion, evaluation of sexual behavior is always show behaviors accompanying , such as tail performed. This can be done either in presence of an movements (flagging), or urethral contractions, but only ovariectomized mare showing strong estrous behavior, or seminal plasma is expelled under low pressure. They in a mare in natural heat. Strong teasing is recommended in dismount slowly, and in the majority of cases do not show cases of timid or novice stallions. Young, especially novice any signs of distress. Stallions with large midline cysts of stallions, as well as some stallions with acquired ejacula- the colliculus seminalis have a signi ficantly higher number tory problems require a longer precopulatory phase than of pelvic thrusts during than normal stallions. older and experienced stallions [9]. If the stallion has Because fluids from the ampullae and the vesicular glands a history of sexual behavior problems, washing the are not voided during emission because of the physical and taking penile swabs are deferred to future sessions so obstruction, ejaculatory process is not triggered, and the as to avoid any distractions. affected stallion may start thrusting again after a short Copulatory behavior is evaluated during semen collec- pause. They often stay mounted on a mare or a dummy tion or natural breeding. Each session is video-recorded without signs of relaxation, and finally slowly dismount. to allow for detailed analysis of all aspects of stallion ’s After prolonged thrusting, a stallion often moves his behavior, as well as a technique of semen collection. A hindquarters sidewise, toward the arti ficial camera should be mounted on a tripod and set for recording handlers. Occasionally, affected stallions try to reposition the entire scene. We find information derived from the themselves vigorously, tossing their head, moving their recorded material very helpful in the majority of cases. In front end up with front feet on the neck of a mare. Special addition, the specialists from other fields of veterinary caution has to be taken while collecting semen from these profession, such as medicine or surgery, can view recorded stallions to avoid injury. sessions and give their opinion regarding the need to Multiple attempts to collect semen are often necessary conduct neurological or lameness examinations. to obtain a semen sample for evaluation. Strong teasing, Ejaculatory dysfunctions in stallions are often associ- application of hot compresses on a base of stallion ’s penis, ated with musculoskeletal problems or with an occlusion of and oxytocin treatment may enhance ejaculatory response. the ampullae of deferent ducts. However, stallions with these conditions display different behavioral symptoms 3.2. Semen Evaluation than stallions with the midline cysts of the colliculus seminalis (Table 2 ). Stallions experiencing acute discomfort Parameters of semen collected from affected stallions because of various musculoskeletal diseases show signs of are very variable. The most frustrating feature is inconsis- pain, such as ear pining, head throws, high pitch vocaliza- tency of semen quality. All semen parameters may be tion, and sudden dismounting. These behaviors occur early normal, but, more often, numbers of spermatozoa are low during the copulatory phase, whereas the speci fic ejacu- (oligospermiadazoospermia); motility of spermatozoa is latory problems are expressed later, during emission or severely affected, or spermatozoa are not motile (asthe- ejaculation itself. Prolonged painful stimuli associated with nozoospermia or necrospermia) ( Table 1 ). The percentage the reproductive tract (stallion ring, etc.) affect libido [10] , of morphologically normal spermatozoa is often low. whereas stallions experiencing ejaculatory dysfunctions However, there are only a few spermatozoa with primary M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 725

Table 2 Behavior symptoms associated with various conditions causing ejaculatory dysfunctions

Behavior Conditions

Musculoskeletal Pain Occluded ampullae of deferent ducts Midline cyst of colliculus seminalis

Libido Normal initially; often worsens if Usually unaffected Unaffected pain symptoms experienced for a prolonged period Ability to mount May be severely affected Unaffected Unaffected Copulatory phase Shorter than normal Longer than normal Longer than normal Pelvic thrusts Lower number than normal Greater number than normal Greater number than normal (approximately (approximately. 8 to 10) 10 to 16); often another sequence of thrusts occurs after a short pause Dismount Sudden, immediately after last Slow, after a short pause following Very slow, after a long pause following a last pelvic thrust a last pelvic thrust pelvic thrust Coupling posture Poor coupling posture; straight back; Normal; properly curved back Normal; properly curved back shifting weight to one side Other behaviors Ear pining; head throws; high pitch None None or sudden repositioning before another expressed during vocalizations; looking to one side series of pelvic thrusts a copulatory phase Ejaculation Normal when pain symptoms are Low number of urethral pulsations, No urethral pulsations, and no fluid expelled; under control but only seminal plasma present; normal, once ejaculatory threshold reached poor pressure of ejaculatory jets Long-term effects Normal sexual behavior if pain Normal sexual behavior once a Continuous or frequently re-occurring symptoms are under control; blockage is resolved ejaculatory difficulties low libido, if pain symptoms are present

morphological defects or immature germ cells in ejacu- essential, and should be conducted carefully. All accessory lates. Usually, there is a high number of spermatozoa with glands, urethra, and the caudal aorta are examined. Location, secondary morphological defects, such as bent tails, distal size, texture, and sensitivity of both ampullae are assessed cytoplasmic droplets, and tailless heads. Occasionally, all first, during rectal palpation. The lumen of the ampullae of semen parameters are consistently good. Just one subtle deferent ducts may be normal, but it may be signi ficantly change occurs unexpectedly; for example, longevity of dilated, especially after unsuccessful attempts to collect sperm motility in extended and cooled semen decreases semen (Fig. 3). Hyperechoic concrements are frequently dramatically. found in the ampullar lumen, especially in the narrow part of The typical picture of semen collected from stallions deferent ducts, distal to the prostatic lobes. These concre- with temporarily plugged ampullae is rarely seen in cases ments are single or numerous, and have a tendency to move discussed in this article. After ampullar occlusion is distal and group together after multiple attempts of a relieved, normal, forceful ejaculation occurs and large stallion to ejaculate ( Fig. 4). Vesicular glands may become numbers of spermatozoa, stored in dilated ampullae, are distended as well, if the ejaculatory process is affected expelled. Concentration of semen is very high and there is (Fig. 5). If the excretory ducts of the vesicular glands are a very high percentage of tailless heads of spermatozoa in compressed for a prolonged period, their contents may such an ejaculate [11] . Ejaculatory dysfunction associated become very thick and form echogenic plugs ( Fig. 6). with the midline cyst of the colliculus seminalis is a chronic Cystic structures are found in various locations. Small condition, and there is no major improvement after cysts of the uterus masculinus are found in up to 50% of obtaining a complete ejaculate. Occasionally, stallions with normal stallions, most often at the level of the neck of the this condition experience transient hemospermia, chronic urinary bladder, between ampullae, which are narrowing oligospermia, asthenozoospermia, or necrospermia. Inter- down in this area toward the colliculus seminalis [12] . The estingly, some stallions expel semen containing a collection presence of these structures usually has no consequences of small aggregations of sperm and bacteria. Other stallions in the stallion ’s ejaculatory function. However, we reported with chronic ejaculatory dif ficulties and midline cyst of the an increased frequency of this feature in the population of colliculus seminalis have hyperechoic plugs in the very stallions with ejaculatory problems [4]. Our recent clinical terminal portions of deferent ducts (distal to ampullae). material suggests that larger cystic structures, exceeding These plugs may be expelled during ejaculation and 1 cm in diameter, and localized more caudally, at the level contain very high numbers of spermatozoa and bacteria as of the seminal colliculus, contribute to the stallion ’s ejac- well. Corynebacterium species was identi fied in the semen ulatory dif ficulties more often. The presence of these cysts of three stallions with these features. We have not seen any is often overlooked because they are localized very distally, in flammatory cells in the expelled plugs or semen in the pelvic urethra, just cranial to the bulbourethral produced by these stallions. glands, but distal to the prostatic isthmus. They usually have an oval shape, but may be also tear-shaped, rectangular, or 3.3. Evaluation of Internal Genitalia spindle-shaped ( Fig. 7 ). An average diameter of these cysts, found in our clinical cases, varied from 1 to 3 cm ( Table 1 ). Rectal palpation and TRUS of internal reproductive They may be well-de fined with hyperechoic walls, or may structures in stallions with ejaculatory dysfunction are be quite dif ficult to delineate. They may also have 726 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731

Fig. 3. Ultrasound images of dilated ampullae of deferent ducts in a stallion with the midline cyst of the colliculus seminalis: ( A) Position of a transducer, ( B) Ultrasound image obtained immediately after the first attempt to collect semen, ( C) Ultrasound image obtained immediately after the second attempt to collect semen (same day as the previous attempt), ( D) Ultrasound image obtained immediately after the third attempt to collect semen (same day as the previous attempt); dilated excretory duct of the vesicular gland visualized on the dorsal aspect of the ampulla. echogenic contents (Fig. 7F). A small collection of non- the epididymal duct may be prominent with a slightly echoic fluid is often seen in the urethral lumen posterior to distended lumen. A mild hydrocele is often seen. the cyst after an unsuccessful attempt to collect semen fi (Fig. 7 B). Other ndings of the ultrasound evaluation of the 4. Treatment and Management internal reproductive tract of the affected stallion are usually unremarkable. Currently, there is no effective treatment for this Urethroscopic evaluation of stallions with ejaculatory condition. However, the affected stallions can be managed fi dysfunction is rarely conducted and the ndings of this successfully, if their problem is recognized early enough to evaluation rarely add to the diagnosis. Slight enlargement properly adjust their mare book, and come up with a set of of the colliculus seminalis is occasionally seen in affected specific procedures, which will enhance a probability of cases. a success. Because there is no guarantee that semen will be successfully collected on any given day, the owners of 3.4. Evaluation of the mares, booked to the affected stallions, should be informed ahead of time of the problem. To enhance the chances for All structures of the scrotum are carefully examined by success, a team working with the stallion should be using manual palpation and ultrasonography. Testes are prepared for the necessity of numerous attempts to collect normal in size and texture, but could be smaller than semen. There should be a plan about how to proceed in the expected for the adult stallions, and/or have a tendency to case of an initial failure. There is no certain protocol equally have soft consistency. Ultrasound evaluation of testicular effective in all cases; a speci fic protocol should be estab- parenchyma is unremarkable. However, some subtle lished for each affected individual stallion. changes may be seen within/or in the vicinity of the Transrectal massage of the ampullae of the deferent epididymides in these stallions. Thin-walled cysts, irre- ducts is rarely effective in stallions with midline cysts of spective of whether they are small or large, are often colliculus seminalis. Although inspissated sperm, which visualized in the area of the epididymal heads. They may be occludes the ampullae, can be manually advanced during single or multiple, and have anechoic contents. In some transrectal massage, the cysts are continuously impinging cases, however, there are hyperechoic areas or concre- on the ejaculatory apparatus and cannot change their ments in the epididymal heads or tails. The distal part of location. Strong teasing and the administration of oxytocin

Fig. 4. Ultrasound images of hyperechoic concrements in deferent ducts in stallions with the midline cyst of colliculus seminalis: ( A) Position of a transducer. (B) Ultrasound image of one, solid concrement (plug) in a narrow part of the terminal part of the deferent duct. ( C) Ultrasound image of the multiple hyperechoic concrements in the terminal part of the deferent duct. M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 727

Fig. 5. Ultrasound images of dilated vesicular glands in a stallion with the midline cyst of the colliculus seminalis: ( A) Position of a transducer. ( B) Ultrasound image obtained immediately after the first attempt to collect semen. ( C) Ultrasound image obtained immediately after the second attempt to collect semen (same day as the previous attempt). ( D) Ultrasound image obtained immediately after the third attempt to collect semen (same day as the previous attempt). shortly before semen collection can be helpful in some the presence of the ovariectomized teaser mare, readily individuals. A combination of pretreatment with imipra- achieved an in the breeding shed and mounted mine (1,200 mg, per os, 2 hours before semen collection), a dummy. Despite good coupling with a dummy, numerous heavy teasing, and treatment with oxytocin (10-30 IU, iv; pelvic thrusting after insertion of the penis into the immediately before semen collection) seems to be most Missouri AV (8 to 9 thrusts) did not yield an ejaculate. The effective. In addition, stallions with chronic ejaculatory attempts to collect semen from this stallion were repeated dysfunction often develop painful sores on the medial side multiple times without a success. All sessions were video- of their carpi, as well as chronic back or hind legs problems, recorded. This material was carefully reviewed and because of the multiple mounts on a dummy or a mare. showed no evidence of discomfort or problems with the These complications may further contribute to problems AV. The stallion showed some strong attempts to ejaculate with ejaculation. Wrapping front limbs (carpi) prevents expressed by one or two urethral contractions accompa- development of sores, and therefore, it is recommended in nied by tail flagging after a series of thrusting, with no all stallions with ejaculatory dysfunctions. The number of ejaculation achieved. There were no early dismounts or attempts to collect semen should be limited so as to signs of relaxation. Additional stimulation, such as hot prevent secondary musculoskeletal problems. Long-term compresses on the base of the penis, or the Colorado model treatment with phenylbutazone can help in managing AV (Animal Reproduction Systems, Chino, CA) was used to potential discomfort during pelvic thrusting. enhance the ejaculatory process. Regardless of the tech- nique used, the stallion ejaculated only occasionally, always 5. Clinical Examples after multiple attempts. Semen quality, when collected, was fair to good. TRUS of this stallion ’s internal genitalia 5.1. Case 1 revealed the oval cystic structure (1.13 cm in diameter) in the pelvic urethra in the close proximity to the bulboure- A 7-year-old Thoroughbred stallion was evaluated as thral glands, behind the prostate ( Fig. 8A). In addition, a potential candidate for teaching veterinary students small hyperechoic concrements were detected in the most (Table 1 ; case 1). The horse was in an excellent body terminal part of each deferent duct. Transurethral endo- condition and showed no abnormalities during a general scopic examination was performed and the colliculus physical examination. The stallion showed a good libido in seminalis was visualized. Simultaneously, TRUS was

Fig. 6. Ultrasound images of the hyperechoic contents in the vesicular glands in a stallion with the midline cyst of colliculus seminalis: ( A) Position of a transducer. ( B) Ultrasound image of the hyperechoic contents in the mid portion of the vesicular glands. ( C) Ultrasound image of the hyperechoic contents in the excretory duct of the vesicular gland. 728 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731

Fig. 7. Ultrasound images of the midline cysts of the seminal colliculus in stallions with ejaculatory problems: ( A) Position of a transducer. ( B) Oval-shaped cyst. (C) Rectangular cyst. ( D) Tear-shaped cyst. ( E) Spindle-shaped cyst and echogenic contents in the terminal . ( F) Echogenic contents inside the cyst. performed. These two techniques performed together a large (4 Â 0.6 cm), spindle-shaped uterus masculinus revealed that the cyst was localized exactly within the lying just underneath the isthmus of the prostate, between colliculus seminalis. There was also a polyp-like structure the very distal parts of the ampullae ( Fig. 9 B). Furthermore, associated with the opening to the left ED. The stallion had there was an oval-shaped midline cyst on the level of the to be euthanized because of the acute onset of equine colliculus seminalis (1 Â 0.8 cm). Before the first attempt to protozoal myeloencephalitis. Postmortem evaluation of the collect semen, distal ampullae were massaged per genital tissues revealed the presence of the multiple cysts and 30 IU of oxytocin were administered intravenously. between the most terminal portions of deferent ducts, The stallion showed excellent libido, readily mounted within the colliculus seminalis, which were signi ficantly a dummy, had multiple thrusts (9 thrusts), but did not occluding their lumen (Fig. 8B ). The cysts were filled with ejaculate. During the second attempt, hot towels were noncellular fluid and had stratified, squamous epithelium applied to the base of the stallion ’s penis and a very small (Fig. 8 C, D). The location, lack of communication with the amount (5 mL) of semen with a “grid-like ” appearance and urethra, lack of spermatozoa in the cystic fluid, and the poor motility of spermatozoa ( <10%) was obtained. Cyto- character of the epithelium suggested that this cyst was logical evaluation revealed that the solid particles, which consistent with what is described in men as a midline cyst gave the semen a “grid-like ” appearance, consisted of of prostate type I [13] . spermatozoa and large numbers of bacteria ( Fig. 9 C). No in flammatory cells were found. Subsequent attempts to 5.2. Case 2 collect semen yielded inconsistent results, despite various combinations of treatment with imipramine, oxytocin, An 8-year-old Quarterhorse stallion was presented to rectal massage of the ampullae, and the application of hot our clinic with a history of ejaculatory dif ficulties ( Table 1 ; compresses. The quality of semen was also inconsistent, case 2). There were always problems with collecting but the motility was generally improving. Further disten- semen from this stallion, but in the past few weeks all tion of distal ampullae, as well as vesicular glands, was attempts to obtain semen failed. General physical exami- observed after unsuccessful attempts to collect semen. nation of the stallion did not reveal any abnormalities, Some improvement in the ability to collect semen was except some fresh abrasions on the medial aspects of his observed after the stallion was given 2 weeks of rest for carpi, most likely because of the multiple mounts on the he aling the carpal wounds, and treatment with phenyl- dummy. Ultrasound evaluation of his external and internal butazone so as to decrease possible musculoskeletal genitalia revealed prominent epididymal ducts and mildly discomfort associated with multiple mounts and pelvic dilated ampullae of deferent ducts. Terminal parts of both thrusts (9 to 16 thrusts). Currently, the stallion continues to deferent ducts (distal to ampullae) contained multiple experience ejaculatory dysfunction. However, strong hyperechoic concrements ( Fig. 9 A). In addition, there was teasing, treatment with imipramine and oxytocin, as well M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 729

Fig. 8. Case 1. ( A) Ultrasound image of the midline cyst of the colliculus seminalis. ( B) Cross-section of the urethra at the level of the colliculus seminalis with the cyst. (C) Microscopic slide with a wall of the midline cyst dlow power. ( D) Microscopic slide with a wall of the midline cyst dhigh power. as additional stimulation of the base of the penis are are short (approx. 2 to 3 mm) and relatively wide (6 to helpful in obtaining semen samples. 7 mm) [7]. Therefore, true EDO rarely occurs in stallions. Cystic structures, which are often seen between ampullae 6. Discussion of the deferent ducts in stallions, usually do not have any clinical significance. Small midline cysts of the colliculus EDs in men are long and narrow, which make them seminalis in stallions may be also asymptomatic. We have prone to obstruction [14] . One to five percent of infertility found such cysts in six animals during the screening cases in men are associated with ED occlusion (EDO) [15] . ultrasound evaluation of the population of 100 fertile One of the early symptoms of this condition is painful stallions [4]. One of these stallions required strong stimu- ejaculation and azoospermia [16] . However, the symptoms lation during semen collection, one stallion had hemo- may be much more subtle in cases of a partial obstruction spermia, and other three had poor quality of semen. Large and show only as mild oligospermia, oligoasthenospermia, cysts in the area of the colliculus seminalis can affect the or poor survival of spermatozoa in vitro and inability to passage of semen through the very terminal part of the fertilize oocytes [16,17] . In contrast to men, EDs in stallions deferent ducts to cause ejaculatory problems [6]. The cystic

Fig. 9. Case 2. ( A) Midline cyst of colliculus seminalis and hyperechoic particles in the terminal seminal tract. ( B) Cystic uterus masculinus dlongitudinal section. (C) Microscopic image of the expelled “grid-like” particles. 730 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 structure found in the stallion with ejaculatory dysfunction successful, cloudy or milky fluid should appear re fluxing in case 1 was obviously compressing the terminal portions from the opened ducts. Even though this procedure is quite of both deferent ducts, excretory ducts of vesicular glands, successful in selected patients, there are some potential as well as EDs. Extensive anatomical and histological complications associated with it, such as watery ejaculate, studies showed that this structure in stallions is of mixed hematuria, epididymitis, seminal vesiculitis, and very rarely embryological origin. The proximal portion is a remnant of incontinence or rectal perforation [15] . Recently, limited the Müllerian ducts, whereas the most distal part comes success was also reported using less invasive techniques, from the [18] . Because the cyst in case 1 such as TRUS-guided ethanol sclerotherapy of the cysts, or had strati fied, squamous epithelium, its origin was most endoscopic dilation of the EDs [26,27] . likely associated with the latter. Because there was no Currently, there is no effective and permanent treatment sperm in the lumen of this cyst, there was no communi- for similar disorders in stallions. However, cannulation of cation between the cyst and the urethra, deferent ducts, or the EDs in stallions can be performed using a long, flexible EDs. These types of cysts have been described in men as the endoscope. Trained theriogenologists use this technique to midline cysts of the prostate, type 1 [13] Other cysts of this aspirate contents of the vesicular glands as well as to area in men can communicate with the urethra (type 2a), or administer antibiotics in cases of seminal vesiculitis. There- the seminal tract (type 2b). Third, there may be cystic fore, aspirating the midline cyst of the colliculus seminalis, dilatations of the ED (type 3). Similar variations of this administering ethanol to its lumen (sclerotherapy), or even structure in stallions have been described. However, an opening the cyst using an electrocautery loop should be appropriate terminology has not been established yet [12] . possible in the affected cases. The effectiveness of tran- We propose to use the existing medical terminology for surethral surgical procedures correcting physical obstruc- different types of cysts (type 1, 2a, 2b, and 3), but we also tions of the EDs in stallions should be explored. There is also propose to replace the term “midline cysts of the prostate ” a need to introduce dynamic imaging techniques, which or “prostatic utricle” with another term,d “midline cysts of would allow more detailed evaluation of the ejaculatory the colliculus seminalis,” because colliculus seminalis in apparatus in stallions. stallions is located behind the caudal edge of the prostate. Various protocols for the diagnosis and treatment of ejaculatory dysfunctions in men, associated with the ejac- References ulatory apparatus, are currently available. Vasography, TRUS, magnetic resonance imaging, and other imaging [1] McDonnell SM. Reproductive behavior of the stallion. Vet Clin North modalities are used [19-21] . Most often, the presence of the Am Equine Pract 1986;2:535-55. so-called midline prostatic cyst is identi fied as a major [2] Martin BB, McDonnell SM, Love CC. Effects of musculoskeletal and neurologic disease on breeding performance in stallions. 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It has been established that fertile classification of midline cysts of the prostate in adults via a trans- fi patients have remarkably consistent ED opening pressure rectal ultrasonography-guided opaci cation and dye-injection study. BJU Int 2008;102:475-8. (<45 cm H 2O), whereas the patients with EDO have [14] Nguyen HT, Etzell J, Turek PJ. Normal human ejaculatory duct significantly higher ED opening pressure than normal anatomy: a study of cadaveric and surgical specimens. J Urol patients [22]. Transurethral resection of the ED is a treat- 1996;155:1639-42. [15] Smith JF, Walsh TJ, Turek PJ. Ejaculatory duct obstruction. Urol Clin ment of choice for EDO in men [24,25] . This is an outpatient North Am 2008;35:221-7. procedure, which in most cases requires only regional [16] Fisch H, Lambert SM, Goluboff ET. Management of ejaculatory duct anesthesia. The colliculus seminalis is resected under direct obstruction: etiology, diagnosis, and treatment. 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